[Docs] Sequence.Social does not exist in code, only README

[velosol]

Describe the bug
The README.md mentions Sequence.Social in the support tables (as Seq. - Social) but there does not appear to be any matching code in https://github.com/microsoft/Recognizers-Text/tree/master/.NET/Microsoft.Recognizers.Text.Sequence/Extractors or e.g. https://github.com/microsoft/Recognizers-Text/tree/master/.NET/Microsoft.Recognizers.Text.Sequence/English/Extractors .

Assuming that 'Social' means 'Social Media' and not 'Social Security Number' (which I would expect under Number) then the 'Mention' Extractors make sense as 'Social Media Mentions' of the form @username implemented by Sequence.Mention.

To Reproduce
N/A beyond inspecting README and repo.

Expected behavior
I expect README, as the initial documentation one sees, to match what is available in code and with minimal ambiguity. I suggest README tables replace 'Seq. - Social' with 'Seq. - Mentions' or 'Seq. - Social Media*' and a footnote that the social media sequence is implemented under Sequence.Mention .

Sample input/output
N/A
Platform (please complete the following information):
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Additional context
N/A